This invention relates to color cathode ray picture tubes, and is addressed specifically to the manufacture of tubes having shadow masks of the tension foil type in association with a substantially flat faceplate. The invention is useful in the manufacture of color tubes of various types, including those used in home entertainment television receivers, and in medium-resolution and high-resolution tubes intended for color monitors.
The tension foil shadow mask is part of the cathode ray tube front assembly, and is located in close adjacency to the faceplate. As used herein, the term "shadow mask" means an apertured metallic foil which may, by way of example, be about 0.001 inch thick, or less. The mask is supported in high tension a predetermined distance from the inner surface of the faceplate; this dimension is known as the "Q-height." As is well known in the art, the shadow mask acts as a color-selection electrode, or "parallax barrier," which ensures that each of the three beams generated by the electron gun located in the neck of the tube lands only on its assigned phosphor deposits.